Method for controlling shifting of a partial double clutch transmission

Abstract

A method of controlling shifting in a transmission having a first partial transmission, designed as a dual-clutch transmission, which comprises first and second clutches by which the dual-clutch transmission can be functionally connected to a turbocharged internal combustion engine. A second partial transmission is arranged in the drive-train, downstream of the dual-clutch transmission, which is in the form of a main transmission that shifts with traction force interruption. To at least reduce traction power loss of the turbocharged engine after a traction shift, during a traction shift involving a gearshift in the main transmission, the clutches are at least partially engaged so as to be braced against one another and produce a torque that acts in opposition to the drive engine by virtue of which, during the traction shift, the supercharge pressure of the drive engine is largely maintained, or at least built up shortly after the traction shift.

The invention claimed is: 
     
       1. A method of controlling shifting in a partial dual-clutch transmission, having a first partial transmission designed as a dual-clutch transmission (DKG) with a dual clutch (DK) comprising a first clutch (K 1 ) and a second clutch (K 2 ) by which the dual-clutch transmission (DKG) is functionally connectable to a drive engine (M) designed as turbocharged internal combustion engine, and with a second partial transmission arranged in a drive-train, downstream from the dual-clutch transmission (DKG), and designed as a main transmission (HG) that shifts with traction force interruption, the method comprising the steps of:
 at least partially engaging the first clutch (K 1 ) and the second clutch (K 2 ) during a traction shift involving a gearshift in the main transmission (HG), so as to brace the first clutch (K 1 ) and the second clutch (K 2 ) against one another and produce a bracing torque acting in opposition to the drive engine (M); and 
 either maintaining or building up a supercharge pressure of the drive engine during the traction shift with the torque acting in opposition to the drive engine, within a predetermined time after the traction shift. 
 
     
     
       2. The method according to  claim 1 , further comprising the step of building up the bracing torque of the dual clutch (DK), by operating one of the first and the second clutches (K 1 , K 2 ) in an engaged condition and operating the other of the first and the second clutches with slip. 
     
     
       3. The method according to  claim 1 , further comprising the step of building up the bracing torque of the dual clutch (DK) by operating both of the first and the second clutches (K 1 , K 2 ) with slip. 
     
     
       4. The method according to  claim 1 , further comprising the step of at the beginning of the traction shift, reducing a load in the main transmission (HG), in that the engine torque is reduced and, if necessary, disengaging one of the first and the second clutches (K 1 , K 2 ) which is currently load-supporting, until a gear, currently engaged in the main transmission (HG), is disengaged while substantially free from load, and immediately after the gear disengagement the dual clutch (DK) is braced so that the torque, acting in opposition to the drive engine (M), is produced and a rotational speed adaptation to produce synchronization of the components of the gear to be engaged that must be shifted takes place, and after the new gear has been engaged a load build-up in the main transmission (HG) occurs, the bracing of the dual clutch (DK) is released by disengaging one of the first and the second clutches (K 1 , K 2 ) while, as the load-supporting clutch in the new gear, the other one of the first and the second clutches (K 1 , K 2 ) either is or remains engaged. 
     
     
       5. The method according to  claim 4 , further comprising the step of adapting the rotational speed place independently of any synchronous shifting clutches present in the main transmission (HG). 
     
     
       6. The method according to  claim 1 , further comprising the step of at the beginning of the traction shift, reducing a load in the main transmission (HG), in that the torque acting in opposition to the drive engine (M) is produced by bracing the dual clutch (DK), the currently not load-supporting one of the first and the second clutches (K 1 , K 2 ) is brought to a slipping condition while the currently load-supporting clutch (K 1 , K 2 ) is or remains engaged or at least partially engaged, until a gear currently engaged in the main transmission (HG) is disengaged while largely free from load, and after the gear is disengaged, a rotational speed adaptation to produce synchronization of the components of a new gear to be engaged that must be shifted occurs, and after the new gear is engaged, a load build-up in the main transmission (HG) occurs, and the bracing of the dual clutch (DK) is released by disengaging one of the first and the second clutches (K 1 , K 2 ) while, as the load-supporting clutch in the new gear, the other one of the first and the second clutches (K 1 , K 2 ) is or remains engaged. 
     
     
       7. The method according to  claim 6 , further comprising the step of during the speed adaptation, adjusting the clutch torques such that the speed of the target gear is reached with a specified dynamic. 
     
     
       8. The method according to  claim 7 , further comprising the step of specifying a maximum possible fuel injection quantity of the drive engine (M) by an engine control system, and adapting the rotational speed by regulating the bracing torque of the dual clutch (DK). 
     
     
       9. The method according to  claim 7 , further comprising the step of specifying a target rotation speed via an engine control system, and varying the bracing torque of the dual clutch (DK) so that the target speed is reached by the engine control system. 
     
     
       10. The method according to  claim 1 , further comprising the step of the supercharge-pressure-relevant bracing of the dual clutch (DK) during a traction shift always occurs if, after the traction shift, an effect of the driving resistance in a newly engaged gear exceeds a suction torque of the engine (M). 
     
     
       11. The method according to  claim 1 , further comprising the step of the supercharge-pressure-relevant bracing of the dual clutch (DK) during a traction shift always occurs if a power demand, indicated by a kick-down or an accelerator pedal position, exceeds a specified threshold value. 
     
     
       12. The method according to  claim 11 , further comprising the step of always performing the supercharge-pressure-relevant bracing of the dual clutch (DK) during the traction shift if this is recognized as appropriate with reference to a predetermined measure of comfort or performance. 
     
     
       13. The method according to  claim 1 , further comprising the step of only bracing the supercharge-pressure-relevant bracing of the dual clutch (DK) during the traction shift, with a currently determined clutch loading, a predetermined load reserve of at least one of the first and the second clutches (K 1 , K 2 ) permits. 
     
     
       14. The method according to  claim 13 , further comprising the step of taking into account situations to be expected shortly for determination of a load reserve of one of the first and the second clutches (K 1 , K 2 ) operated with slip. 
     
     
       15. The method according to  claim 13 , further comprising the step of when taking into account parameters which are at least one of clutch-specific, surroundings-specific and specifically relating to a field of use of the vehicle for determining the load reserve of one of the first and the second clutches (K 1 , K 2 ) operated with slip. 
     
     
       16. A method of controlling shifting in a partial dual-clutch transmission of a utility vehicle, having a dual-clutch transmission (DKG) and a main transmission (HG), the dual-clutch transmission comprising first and second clutches (K 1 , K 2 ) which functionally couple the dual-clutch transmission (DKG) to a turbocharged internal combustion engine, and the main transmission shifting with an interruption in traction force and being arranged in a drive-train downstream from the dual-clutch transmission, the method comprising the steps of:
 initiating a traction shift in the main transmission to shift from a current gear to a new gear; 
 at least partially engaging both the first clutch and the second clutch to brace the first and the second clutches against one another and produce a torque which is acting in opposition to torque that is produced by the turbocharged internal combustion engine; 
 disengaging the current gear; 
 engage the new gear; and 
 one of maintaining a supercharge pressure of the turbocharged internal combustion engine, during the traction shift, or building up the supercharge pressure of the turbocharged internal combustion engine shortly after the traction shift.